rework

.github/workflows/go.yml

@@ -0,0 +1,28 @@
+# This workflow will build a golang project
+# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-go
+
+name: Go
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+
+jobs:
+
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Set up Go
+      uses: actions/setup-go@v3
+      with:
+        go-version: 1.22
+
+    - name: Build
+      run: go build -v ./...
+
+    - name: Test
+      run: go test -v ./...

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2024 Martin Kopka Drlík
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -0,0 +1,3 @@
+# rex
+
+Exploring incomplete data for relational database model.

box/relation.go

@@ -0,0 +1,115 @@
+package box
+
+import (
+	"fmt"
+	"io"
+	"iter"
+	"strings"
+	"unicode/utf8"
+)
+
+type relationBox struct {
+	schema []string
+	rows   []map[string]string
+	max    map[string]int
+}
+
+func Relation(schema []string, tuples iter.Seq[map[string]any]) interface{ String() string } {
+	rb := &relationBox{
+		schema: schema,
+		rows:   []map[string]string{},
+		max:    map[string]int{},
+	}
+	for _, s := range rb.schema {
+		rb.max[s] = utf8.RuneCountInString(s)
+	}
+	for t := range tuples {
+		rb.addRow(t)
+	}
+	return rb
+}
+
+func (t *relationBox) addRow(tuple map[string]any) {
+	str := func(v any) string { return fmt.Sprintf("%v", v) }
+	row := map[string]string{}
+	for k, v := range tuple {
+		s := str(v)
+		if l := utf8.RuneCountInString(s); t.max[k] < l {
+			t.max[k] = l
+		}
+		row[k] = s
+	}
+	t.rows = append(t.rows, row)
+}
+
+func (t *relationBox) String() string {
+	sb := &strings.Builder{}
+	t.writeTop(sb)
+	t.writeHeader(sb)
+	if len(t.rows) > 0 {
+		t.writeSeparator(sb)
+		t.writeRows(sb)
+	}
+	t.writeBottom(sb)
+	return sb.String()
+}
+
+func (t *relationBox) writeTop(w io.Writer) {
+	// ┏━━━━━━┯━━━━━━┓
+	t.writeRow(w, "┏", "┯", "┓", func(s string) string {
+		return strings.Repeat("━", t.max[s]+2)
+	})
+}
+
+func (t *relationBox) writeHeader(w io.Writer) {
+	// ┃    x │    y ┃
+	t.writeRow(w, "┃", "│", "┃", func(s string) string {
+		return fmt.Sprintf(" %s ", t.pad(s, s))
+	})
+}
+
+func (t *relationBox) writeSeparator(w io.Writer) {
+	// ┠──────┼──────┨
+	t.writeRow(w, "┠", "┼", "┨", func(s string) string {
+		return strings.Repeat("─", t.max[s]+2)
+	})
+}
+
+func (t *relationBox) writeRows(w io.Writer) {
+	for _, row := range t.rows {
+		// ┃ 2023 │ 2024 ┃
+		t.writeRow(w, "┃", "│", "┃", func(s string) string {
+			v, ok := row[s]
+			return fmt.Sprintf(" %s ", t.pad(s, val(v, ok)))
+		})
+	}
+}
+
+func (t *relationBox) writeBottom(w io.Writer) {
+	// ┗━━━━━━┷━━━━━━┛
+	t.writeRow(w, "┗", "┷", "┛", func(s string) string {
+		return strings.Repeat("━", t.max[s]+2)
+	})
+}
+
+func val(v string, ok bool) string {
+	if ok {
+		return v
+	}
+	return "?"
+}
+
+func (t *relationBox) writeRow(w io.Writer, left, middle, right string, valueFunc func(string) string) {
+	fmt.Fprint(w, left)
+	for i, s := range t.schema {
+		if i > 0 {
+			fmt.Fprint(w, middle)
+		}
+		fmt.Fprint(w, valueFunc(s))
+	}
+	fmt.Fprintln(w, right)
+}
+
+func (bt *relationBox) pad(s, v string) string {
+	return fmt.Sprintf("%s%s", v, strings.Repeat(" ", bt.max[s]-utf8.RuneCountInString(v)))
+}

box/relation_test.go

@@ -0,0 +1,32 @@
+package box_test
+
+import (
+	"fmt"
+	"slices"
+
+	"github.com/martindrlik/rex/box"
+)
+
+func ExampleRelation() {
+	fmt.Println(box.Relation(
+		[]string{"title", "year"},
+		slices.Values([]map[string]any{
+			{"title": "Adventure Time", "year": 2010},
+			{"title": "What We Do in the Shadows", "year": 2019},
+			{"title": "The Last of Us"}})))
+
+	fmt.Println(box.Relation([]string{"empty", "table"}, slices.Values([]map[string]any{})))
+
+	// Output:
+	// ┏━━━━━━━━━━━━━━━━━━━━━━━━━━━┯━━━━━━┓
+	// ┃ title                     │ year ┃
+	// ┠───────────────────────────┼──────┨
+	// ┃ Adventure Time            │ 2010 ┃
+	// ┃ What We Do in the Shadows │ 2019 ┃
+	// ┃ The Last of Us            │ ?    ┃
+	// ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━┷━━━━━━┛
+	//
+	// ┏━━━━━━━┯━━━━━━━┓
+	// ┃ empty │ table ┃
+	// ┗━━━━━━━┷━━━━━━━┛
+}

example-difference.sh

@@ -0,0 +1,9 @@
+#!/bin/zsh
+
+table_one='[{"year": 2049}, {"year": 2050}]'
+table_two='[{"year": 2050}]'
+result=`go run . difference -ia $table_one -ia $table_two -of json`
+
+echo "Table 1: $table_one"
+echo "Table 2: $table_two"
+echo "Result:  $result"

example-natural-join.sh

@@ -0,0 +1,17 @@
+#!/bin/zsh
+
+cast='[{"movie_id": "br2049", "actor_id": "rg", "character_id": "br2049k"}]'
+movies='[{"movie_id": "br2049", "movie_name": "Blade Runner 2049", "movie_release_year": 2017}]'
+actors='[{"actor_id": "rg", "actor_name": "Ryan Gosling"}]'
+characters='[{"character_id": "br2049k", "character_name": "K"}]'
+
+result=`go run . natural-join -ia $cast -ia $movies -of json`
+result=`go run . natural-join -ia $result -ia $actors -of json`
+result=`go run . natural-join -ia $result -ia $characters -of json movie_name actor_name character_name`
+
+echo "Cast:       $cast"
+echo "Movies:     $movies"
+echo "Actors:     $actors"
+echo "Characters: $characters"
+echo "Projection: {\"movie_name\", \"actor_name\", \"character_name\"}"
+echo "Result:     $result"

example-union.sh

@@ -0,0 +1,9 @@
+#!/bin/zsh
+
+table_one='[{"year": 2049}]'
+table_two='[{"year": 2050}]'
+result=`go run . union -ia $table_one -ia $table_two -of json`
+
+echo "Table 1: $table_one"
+echo "Table 2: $table_two"
+echo "Result:  $result"

go.mod

@@ -0,0 +1,3 @@
+module github.com/martindrlik/rex
+
+go 1.23.1

go.work

@@ -0,0 +1,3 @@
+go 1.23.1
+
+use .